首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   94316篇
  免费   45171篇
  国内免费   105篇
耳鼻咽喉   1813篇
儿科学   4863篇
妇产科学   1000篇
基础医学   18352篇
口腔科学   5738篇
临床医学   13707篇
内科学   27963篇
皮肤病学   7854篇
神经病学   14870篇
特种医学   2628篇
外科学   16841篇
综合类   133篇
现状与发展   1篇
一般理论   34篇
预防医学   6075篇
眼科学   1525篇
药学   6878篇
中国医学   1097篇
肿瘤学   8220篇
  2023年   145篇
  2022年   311篇
  2021年   1822篇
  2020年   5308篇
  2019年   11216篇
  2018年   10583篇
  2017年   11720篇
  2016年   12351篇
  2015年   12274篇
  2014年   12326篇
  2013年   12966篇
  2012年   5349篇
  2011年   5415篇
  2010年   9579篇
  2009年   5951篇
  2008年   3305篇
  2007年   2210篇
  2006年   2256篇
  2005年   1928篇
  2004年   1834篇
  2003年   1734篇
  2002年   1745篇
  2001年   1314篇
  2000年   1324篇
  1999年   790篇
  1998年   223篇
  1997年   180篇
  1996年   145篇
  1995年   129篇
  1994年   132篇
  1993年   115篇
  1992年   293篇
  1991年   260篇
  1990年   242篇
  1989年   225篇
  1988年   165篇
  1987年   152篇
  1986年   149篇
  1985年   176篇
  1984年   107篇
  1983年   83篇
  1982年   58篇
  1980年   57篇
  1979年   90篇
  1978年   91篇
  1976年   61篇
  1975年   85篇
  1974年   87篇
  1973年   76篇
  1972年   57篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Background: To assess consumers’ acceptance of a new fibre, it is essential to evaluate its digestive tolerance after ingestion. We aimed to determine the tolerance of increasing dosages of Promitor? Soluble Gluco Fibre (SGF; Tate&Lyle, Hoffman Estates, IL, USA) up to 70 g fibre per day using a validated gastrointestinal composite score. Methods: A composite score of gastrointestinal tolerance integrating gastrointestinal symptoms, stool frequency and consistency was applied. To statistically validate this composite score, the gastrointestinal tolerance of inulin (10 g versus 20 g containing, respectively, 9 g versus 18 g of fibre) was assessed in 18 healthy volunteers in a randomised double‐blind placebo‐controlled cross‐over study. Second, in a double‐blind placebo‐controlled cross‐over study with 20 healthy volunteers, the gastrointestinal tolerance of SGF in both acute and ‘spread over the day’ conditions of consumption was assessed. Results: By contrast to 10 g, 20 g of inulin demonstrated a significant difference in composite score compared to placebo [P < 0.001, difference = 7.6; 95% confidence interval (CI) = 3.8–11.3]. These values were considered as reference during the second study. In acute conditions, 40 g of SGF fibre was the highest (threshold) dose tested that indicates the digestive tolerance criteria (difference from placebo on the composite score <7.6 and upper limit of the 95% CI <11.3); this is twice the amount tolerated for inulin. In ‘spread over the day’ conditions, 65 g of SGF fibre was the threshold dose (P < 0.001, difference = 6.5; 95% CI = 3.4–9.5). Conclusions: The results of the present study demonstrate that 40 g of SGF fibre, when consumed as a single dose, and 65 g of SGF fibre, when consumed in multiple‐doses, across the day are well‐tolerated by healthy volunteers.  相似文献   
992.
Aims: Bone marrow (BM) biopsies of some mucosa‐associated lymphoid tissue (MALT) lymphoma patients show scattered or small clusters of CD20+ cells without definite lesions (subtle CD20 positivity). The aim of this study was to evaluate the clinical significance of BM involvement and subtle CD20 positivity in 122 patients diagnosed with MALT lymphoma. Methods and results: Patients were divided into three categories: BM involvement [BM(+)], subtle CD20 positivity, and no BM involvement [BM(?)]. Eleven (9%) showed BM involvement, and 17 (14%) showed subtle CD20 positivity. BM(+) patients had significantly worse progression‐free survival (PFS) than BM(?) patients [hazard ratio (HR) 6.25, P = 0.01], but there was no significant difference between subtle CD20 positivity and BM(?) patients. Patients with >30 CD3+ cells among 100 nucleated cells in the areas with increased numbers of CD3+ cells had significantly worse PFS than those with <15 CD3+ cells (HR 5.49, P = 0.02). BM(+) patients with >30 CD3+ cells had worse PFS than those with ≤30 CD3+ cells (P = 0.029), with an extent of BM(+) involvement of >10% positively correlating with >30 CD3+ cells (P = 0.015). Conclusions: Patients with BM(+) MALT lymphoma showed significantly worse PFS than those with subtle CD20 positivity and BM(?) MALT lymphoma, but the PFS of patients with subtle CD20 positivity MALT lymphoma was not significantly different from that of those with BM(?) MALT lymphoma. Increased numbers of BM T cells in MALT lymphoma patients might be suggestive of a worse prognosis.  相似文献   
993.
994.
Post‐transplant infections in allogeneic haematopoietic cell transplant (allo‐HCT) recipients often have severe consequences. This is especially the case when dealing with zygomycete infections where the result is often fatal. A major problem when dealing with zygomycete infections is the need for an accurate and fast diagnosis as the phylum is highly resistant towards the conventional antifungals. We herein describe a non‐fatal case of Lichtheimia corymbifera infection in an allo‐HCT recipient.  相似文献   
995.
Pure parahydrogen (pH2) is the prerequisite for optimal pH2‐based hyperpolarization experiments, promising approaches to access the hidden orders of magnitude of MR signals. pH2 production on‐site in medical research centers is vital for the proliferation of these technologies in the life sciences. However, previously suggested designs do not meet our requirements for safety or production performance (flow rate, pressure or enrichment). In this article, we present the safety concept, design and installation of a pH2 converter, operated in a clinical setting. The apparatus produces a continuous flow of four standard liters per minute of ≈98% enriched pH2 at a pressure maximum of 50 bar. The entire production cycle, including cleaning and cooling to 25 K, takes less than 5 h, only ≈45 min of which are required for actual pH2 conversion. A fast and simple quantification procedure is described. The lifetimes of pH2 in a glass vial and aluminum storage cylinder are measured to be T1C(glass vial) = 822 ± 29 min and T1C(Al cylinder) = 129 ± 36 days, thus providing sufficiently long storage intervals and allowing the application of pH2 on demand. A dependence of line width on pH2 enrichment is observed. As examples, 1H hyperpolarization of pyridine and 13C hyperpolarization of hydroxyethylpropionate are presented. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   
996.
997.
The purpose of this study was to evaluate the association between ATM, TP53 and MDM2 polymorphisms in prostate cancer patients and morbidity after radiotherapy. The presence of ATM (rs1801516), TP53 (rs1042522, rs1800371, rs17878362, rs17883323, and rs35117667), and MDM2 (rs2279744) polymorphisms was assessed by direct sequencing of PCR fragments from 48 patients with histologically proven prostate adenocarcinoma and treated with external beam radiation. The side effects were classified according to the Radiation Therapy Oncology Group (RTOG) score. The results showed no association between clinical characteristics and the development of radiation toxicities (P > 0.05). The C>T transition in the position 16273 (intron 3) of TP53 (rs35117667) was significantly associated with the risk of acute skin toxicity (OR: 0.0072, 95% CI 0.0002–0.227, P = 0.003). The intronic TP53 polymorphism at position 16250 (rs17883323) was associated with chronic urinary toxicity (OR: 0.071, 95%CI 0.006–0.784, P = 0.032). No significant associations were found for the remaining polymorphisms (P > 0.05). The results show that clinical characteristics were not determinant on the developing of radiation sensitivity in prostate cancer patients, and intronic TP53 polymorphisms would be associated with increased acute and chronic radiation toxicities. These observations corroborate the importance of investigating the genetic profile to predict adverse side effects in patients undergoing radiotherapy.  相似文献   
998.
999.
Glutamate is an excitatory neurotransmitter that has been shown to regulate the proliferation, migration and survival of neuronal progenitors in the central nervous system through its action on metabotropic and ionotropic glutamate receptors (GluRs). Antagonists of ionotropic GluRs have been shown to cause a rapid and reversible change in melanocyte dendritic morphology, which is associated with the disorganization of actin and tubulin microfilaments in the cytoskeleton. Intracellular expression of microtubule‐associated protein (MAP) 2a affects the assembly, stabilization and bundling of microtubules in melanoma cells; stimulates the development of dendrites; and suppresses melanoma cell migration and invasion. In this study, we investigated the relationship between glutamate‐mediated signalling and microtubules, cell dendritic morphology and melanoma cell motility. We found that metabotropic GluR1 and N‐methyl‐d ‐aspartate receptor antagonists increased dendritic branching and inhibited the motility, migration and proliferation of melanoma cells. We also demonstrated that the invasion and motility of melanoma cells are significantly inhibited by the combination of increased expression of MAP2a and either metabotropic GluR1 or N‐methyl‐d ‐aspartate receptor antagonists. Moreover, the blockade of glutamate receptors inhibited melanoma growth in vivo. Collectively, these results demonstrate the importance of glutamate signalling in human melanoma and suggest that the blockade of glutamate receptors is a promising novel therapy for treating melanoma.  相似文献   
1000.
Aim The magnetic anal sphincter (MAS) is a recent surgical innovation for severe faecal incontinence (FI). With its place in the treatment algorithm of FI yet to be defined, we report a nonrandomized comparison between MAS and sacral nerve stimulation (SNS) in a single‐centre cohort of patients with FI. Method Data were reviewed from prospective databases. From December 2008 to December 2010, 12 women [median age 65 (42–76) years], having FI for a median of 6.5 years, were implanted with a MAS. Sixteen women, of similar age, preoperative function scores, aetiology and duration of incontinence, and implanted with a permanent SNS pulse generator during the same period, served as a reference group. The duration of hospital stay, complications, change in incontinence and quality of life scores and anal physiology were compared between the two groups. Results The duration of follow up was similar [MAS = 18 (8–30) months vs SNS = 22 (10–28) months; P = 0.318]. Four patients with MAS experienced a 30‐day complication, and the device was removed from one patient in each group. A significant improvement in incontinence (P < 0.001) and quality‐of‐life scores (P < 0.04) occurred in both groups. Mean anal resting pressure increased significantly in patients implanted with a MAS (P = 0.027). Conclusion In this single‐centre nonrandomized cohort of FI patients, MAS was as effective as SNS in improving continence and quality of life, with similar morbidity. These results can now serve as a prelude to a randomized trial comparing the procedures.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号